 His magnum opus "Keralathile Pakshikal" (Birds of Kerala) first published in 1958 is considered to be a classic in Malayalam.Described with illustrations of 261 birds found in Kerala, it is considered a unique work among Indian languages.A collection of his essays on environment, bird watching and birds titled "Pullu Thottu Poonara Vare" won the award of the State Department of Science, Technology and environment for popular Science writing and also the I. C. Chacko Endowment prize by the Kerala Sahitya Academy.